Support for Language Server Protocol

[svenefftinge]

##The VSCode team has recently published the version 2.0 of their language-server protocol. The goal is to define common API for editors such as VSCode or Che to interact with language services like

• TypeScript language services
• OmniSharp (C#)
• Tern or the recently announced Orion JS services
• Ensime (for Scala and Java)
• and probably more (please add them to this ticket).

We have started using this protocol for communication between Che and Xtext and would like to move the Che part here and collaborate on the development. @evidolob: could you create a branch, against which we can make a PR with the basic projects we have created so far?

Tasks in this Epic includes part 1 of implementation:

• Dependency: Agent deployment and management Machine Agent specification and implementation #1823
• Language Server Protocol: Respect Language Server capabilities on IDE client Language Server Protocol: Respect Language Server capabilities on IDE client #1789
• Shows errors and warnings inside editor.
• Intellisense - auto-completion in a context aware setting
• Goto Definition [languageserver] Goto Definition #1423
• Language Server Protocol: Find Reference [languageserver] Find Reference #1421
• Language Server Protocol: Implement client part for "Go To Symbol" feature Language Server Protocol: Implement client part for "Go To Symbol" feature #1791
• Workspace symbols to list project-wide symbols matching a query string.
• Language Server Protocol: Implement document formatting Language Server Protocol: Implement document formatting #1788
• Language Server Protocol: Hover feature Language Server Protocol: Hover feature #1800
• Language Server Protocol: Signature Help feature Language Server Protocol: Signature Help feature #1801
• Language Server Protocol: Refactor Symbol navigation UI Language Server Protocol: Refactor Symbol navigation UI #1809
• Language Server Protocol: Support incremental updates [languageserver] Support incremental updates #1425

Language Server Agents.

LS agents are injected into workspace configuration:
“agents” : [“org.eclipse.che.ls.json”, “org.eclipse.che.ls.csharp”]
LS agents and LS binaries are located at remote storage. For the time being it is Codenvy Update Server. Agents are available by the following urls:
https://codenvy.com/update/repository/public/download/org.eclipse.che.ls.json
https://codenvy.com/update/repository/public/download/org.eclipse.che.ls.csharp
When workspace is created agents are being applied. Basically it means agents script execution over running instance. After that LS can be started on demand when user opens files associated with installed LS.

• Dependency: Agent deployment and management Machine Agent specification and implementation #1823

Bug:

Code Assistant and Code Validation don't work for C# #2509

Initialize process:

• User opens file with LS support.
• LS Editor provider calls vs-agent to initialize LS.
• LanguageRegistryService on vs-agent calls LanguageServerRegistry to find and start LS.
• LanguageServerRegistry launch LS.
• When new LS is launched and initialized, LS capabilities passed to IDE.
• IDE use LS capabilities to create editor and open file.
• Language Server Protocol: Respect Language Server capabilities on IDE client Language Server Protocol: Respect Language Server capabilities on IDE client #1789

Diagnostics

RI: C#, JSON

• Shows errors and warnings inside editor.

Completion (IntelliSense)

RI: C#, JSON

• Intellisense - auto-completion in a context aware setting

Is a context-aware code completion feature in some programming environments that speeds up the process of coding applications by reducing typos and other common mistakes. Attempts to do this are usually done through auto completion popups when typing, querying parameters of functions, query hints related to syntax errors, etc.

Goto Definition

RI: C#

• Goto Definition [languageserver] Goto Definition #1423

Perform search for symbol definition and allows to navigate.

Find References

RI: C#

• Language Server Protocol: Find Reference [languageserver] Find Reference #1421

Search project-wide references for the symbol denoted by the given text

Document Symbols

RI: JSON

• Language Server Protocol: Implement client part for "Go To Symbol" feature Language Server Protocol: Implement client part for "Go To Symbol" feature #1791

Allow to view and navigate document symbols. In most cases it’s can be described as flat outline

Workspace Symbols

RI: C#

• Workspace symbox to list project-wide symbols matching a query string.
  Workspace symbols is the list project-wide symbols matching the query string. It’s allow to navigate not only for file or class name but for method or field.

Document Formatting

RI: JSON

• Language Server Protocol: Implement document formatting Language Server Protocol: Implement document formatting #1788

Format all document.

Document Range Formatting

RI: C#, JSON

• Language Server Protocol: Implement document formatting Language Server Protocol: Implement document formatting #1788

Format selected range in document.

Document on Type Formatting

RI: C#

• Language Server Protocol: Implement document formatting Language Server Protocol: Implement document formatting #1788

Automatically invoke formatting after special character typed.

Hover

RI: C#, JSON

• Language Server Protocol: Hover feature Language Server Protocol: Hover feature #1800

The hover shows useful information, such as types of symbols, or, in the case of CSS below, the shape of the HTML that would match a certain CSS rule:

Or for java hover may show javadoc:

Signature Help

RI: C#

• Language Server Protocol: Signature Help feature Language Server Protocol: Signature Help feature #1801

Shows signature information at a given cursor position. For strongly typed programming languages it’s may shows method parameters types:

[svenefftinge]

Also we have defined the interfaces of the protocol in Java. And made it available here : https://github.com/TypeFox/ls-api

[evidolob]

I create branch named "language-server" https://github.com/eclipse/che/tree/language-server

[nadako]

Nice, this is exactly what I had in mind when I started developing haxe-languageserver - that not only VSCode can implement and make use of that protocol, but any editor/IDE! Looking forward for it to be implemented in Eclipse, so I could try adding Haxe support for it, using the language server.

[TylerJewell]

@tolusha @evidolob @gazarenkov @vkuznyetsov - please, can we link in any dependency issues related to agent deployment and end user UX that are related to how a user will add / remove language servers within a workspace? without seeing the full end user workflow issues that we need to handle, it will be hard to understand what the real definition of done is here.

[tolusha]

#1823

[kaloyan-raev]

I want to prototype a PHP IntelliSense support in Che. I want to take advantage of the Crane language server, which provides the PHP IntelliSense in VSCode: https://github.com/HvyIndustries/crane

As far as I understand, the support for the language server protocol in Che is currently a work in progress and it is not available in the master branch yet.

Could you tell me how to setup my dev environment, so I can start experimenting?

[TylerJewell]

@evidolob @tolusha @vparfonov - FYI - can we document some setup tasks for the community to test our work as we go along?

[kaloyan-raev]

I was able to build the branch from the root pom.xml after deleting a couple of test files that were causing compilation errors.

Now I am exploring how the C# support is implemented. I have a Java workspace in my local Che. I created a new C# file. If I open it in the editor, I get an "Initializing Language Server for cs" progress message and the IDE freezes.

It looks like the C# language server cannot be started. Any hints how to troubleshoot?

[kaloyan-raev]

Same story with the JSON language server. There the code for launching the server is simpler and I found that the /home/user/che-agents/ls-json/launch.sh script is missing. I guess this is related to #2032 and these launch.sh are not available yet...